Abstract
Investigation was made on the components of integrated management of tomato wilt complex. Effects of anatomical and biochemical composition, varietal resistance, use of antagonist, plant extract and agronomic practices such as shifting of sowing date, seed selection and soil amendments on tomato wilt incidence were studied. Histopathological studies showed that F. oxysporum f. sp. lycopersici and R. solanacearum both the pathogens entered into the plant through hairs (mainly bacteria), some sites located over the epidermis and the point of formation of lateral roots. Comparatively thickened, tightly arranged small sized cells with more lignifications in cortical region in the variety Manik were less affected by both the pathogens. Higher content of ascorbic acid, total sugar, reducing sugar and phenol in leaf, stem and root were detected as components of varietal resistance to F. oxysporum f. sp. lycopersici and R. solanacearum. Field survey under natural conditions revealed that variation exists in tomato lines/varieties available in Bangladesh for wilt complex. Under induced epiphytotic conditions the mutant line TM16, the variety King Kong and Shila showed 94.4, 89.1 and 87.9% less fusarium wilt infection than Pusa Ruby. The mutant line TM15 and the cultivars King Kong had no infection against bacterial wilt. In winter season fusarium and bacterial wilt developed less as compared to summer season. The incidence of fusarium and bacterial wilt was reduced by 50.14% and 32.00%, respectively when tomato plants were planted on the 16th November. Bavistin at 2000 ppm and cupravit at 3000 ppm were found most effective in reducing fusarium wilt and bacterial wilt by 52.13% and 82.00%, respectively. In vitro, Trichoderma harzianum and T. viride significantly reduced growth of F. oxysporum f. sp. lycopersici with 81.4 and 74.7% inhibition, respectively. Culture filtrates of T. harzianum also reduced the mycelial growth of the pathogen. T. harzianum showed higher seed germination 78.61% while T. viride showed higher vigour index (738.3%). The formulations of T. harzianum as suspension resulted in significantly higher seed germinations (88.6%) and better vigour index (910.3%) than talcum powder. T. harzianum as oat culture exhibited significantly the lowest percent disease incidence (41.3%) in the pot experiment. Biskatali had an excellent effect in inhibiting the colony growth of the test bacteria (87.4%) and also the fungus (24.4%) compared with control. Application of groundnut oilcake and soybean oil cake as preventive measure was conspicuously superior and reduced the incidence of fusarium and bacterial wilt to the extent of 87.8% and 60.5%, respectively. The highest yield plant⁻¹ (2.12 kg) against fusarium wilt and 3.61 kg against R. solanacearum was observed in plot where combined treatments (Lime + all oilcakes + bavistin for fusarium and lime + all oilcakes + cupravit for bacteria) were applied. Planting tomato from the clean seeds of Manik and Pusa Ruby on the 16 November, application of bavistin at 2000 ppm or 3000 ppm, application of T. viride as oat culture at 22 days after planting and groundnut oilcake as 15 days before planting completely inhibited the wilting effect due to F. oxysporum f. sp. lycopersici infection and also promoted plant growth.